Reassigning signals to cable channels

ABSTRACT

Devices, systems, methods, and other embodiments associated assigning signals to cable channels are described. One example device includes a networking device that includes a transceiver to connect to a cable and communicate signal over the cable to a remote terminal. The cable can include two or more cable channels to carry signals. If a cable channel fails to operate, a switching logic reassigns signals initially carried on the failed cable channel to another cable channel.

CROSS REFERENCE TO RELATED APPLICATIONS

This disclosure is a continuation of U.S. application Ser. No.12/266,607 filed on Nov. 7, 2008, now U.S. Pat. No. 8,295,163 whichclaims priority under 35 U.S.C. §119(e) to U.S. Provisional ApplicationSer. No. 60/988,595 filed on Nov. 16, 2007, which is incorporated hereinby reference in its entirety.

BACKGROUND

Computing devices are typically connected to a network with a networkconnection device. In one example, the network connection device is anEthernet network device that connects a device to an Ethernet network.Some network connection devices communicate over a physical networkcable. The cable may have multiple cable channels (e.g. multiple wires)that can carry different signals.

To standardize network wiring, organizations such as the Institute ofElectrical and Electronics Engineers (IEEE) have created standards thatassign signals to specific cable channels. Network devices that operatewith the standard will transmit and receive signals on pin connectionsthat correspond to the assigned cable channels. However, when even asingle channel becomes inoperable (e.g. one wire breaks), communicationover the cable may not function properly or may even become entirelyinoperable.

SUMMARY

An example embodiment includes a networking device comprised of anetwork interface to connect to a cable and communicate over the cableto a remote terminal. The cable includes two or more cable channels tocarry signals. The network device further includes a cable tester and aswitching logic. The cable tester is configured to test whether a cablechannel has failed. Upon detecting a failed cable channel, the switchinglogic reassigns signals initially carried on the failed cable channel toanother cable channel in the cable.

Another embodiment includes a negotiation logic to negotiate with theremote terminal to reassign the signals from the failed cable channel tothe second cable channel.

In another embodiment, the negotiation logic is configured to negotiateassigning fewer signals on fewer cable channels in the cable, upondetecting the failed cable channel.

In one embodiment, the negotiation logic is configured to negotiateoperating the two or more cable channels at a lower operating speed,upon detecting the failed cable channel.

In another embodiment, the negotiation logic is configured to use atleast one channel that is operational to communicate with the remoteterminal connected to the other end of the cable.

In some embodiments, the network interface is operable to be configuredto communicate signals to the cable as defined by the 1000Base-Tsignaling standard. Upon the detecting the failed cable channel, thenetwork interface is further operable to be configured to communicatesignals to the cable at speeds defined by one of: the 100Base-TXsignaling standard or the 10Base-T signaling standard.

In one embodiment, the switching logic is configured to cause thenetwork interface to reconfigure signal communications from a firstcommunication protocol to a different communication protocol that usesfewer cable channels.

In another embodiment, the port is configured to interface to aregistered jack RJ45 having eight pins representing cable channels one,two, three and four. The switching logic is further configured toconnect the first cable channel to pin numbers four and five, the secondcable channel to pin numbers three and six, the third cable channel topin numbers one and two, and the forth cable channel to pin numbersseven and eight.

In another embodiment, the switching logic is operable to reassign afailed cable channel on cable channels two or three to channels one orfour.

In some embodiments, the cable tester is a Virtual Cable Tester (VTC)for detecting a failed cable channel.

In another embodiment, the network device further includes a timerconfigured to determine a time value since previous signal activity onthe failed cable channel. The failed cable channel is then tested by thecable tester upon the time value exceeding a predetermined time value.

In another embodiment, the cable tester is configured to transmit a testsignal on the first cable channel in order to measure a signal amplitudeand to calculate a length the test signal travels. The cable tester isfurther configured to determine where the failed cable channel hasfailed based on the signal amplitude and the length.

In one embodiment, the cable tester is configured to measure anamplitude of a reflected signal derived from the test signal.

In one embodiment, the network interface is operable to communicate thereassigned signals over the second cable channel at a slower speed thanwhen the signals were communicated over the first cable channel.

In one embodiment, the network interface is configured to operate thefailed cable channel at about a 1000 Megabits/second rate before thechannel failed. The network interface is also configured to operate theanother cable channel at about a 10 Megabits/second rate or about a 100Megabits/second rate.

In another embodiment, the network interlace includes pins configured toconnect to four twisted pairs of wire with each pair associated with acable channel.

In another embodiment, the networking device includes a negotiationlogic operable to cause the remote terminal to be reconfigured tooperate with the reassigned signals on the second channel.

In one embodiment, the networking device is at least one of Institute ofElectrical and Electronic Engineers (IEEE) 802.3ab, 802.3i, and 802.3ucompliant.

In another embodiment, the network device is implemented in one of ahigh definition television, a vehicle, a cellular phone, a set top box,a media player, and Voice over Internet Protocol (VoIP) phone.

In one embodiment, the network interface is configured to connect to aCategory 5 (Cat 5) cable.

In another embodiment, the network device is a PHY-Transceiver.

Another example embodiment includes a method. The method includestransmitting and receiving signals over a cable, where the cableincludes multiple cable channels; determining that a first cable channelis inoperable; and reassigning signals initially carried on the firstcable channel to a second cable channel in the cable.

In one embodiment, the transmitting and receiving is performed by alocal PHY-Transceiver connected at one end of the cable thatcommunicates with a remote PHY-Transceiver connected to the cable. Themethod further includes, responsive to determining that the first cablechannel is inoperative, causing the remote PHY-Transceiver to negotiatea reassignment of signals to the second cable channel.

Another embodiment includes a PHY-Transceiver. The PHY-Transceiverincludes a port to connect to a cable and communicate over the cable toa remote PHY-transceiver. The cable includes two or more twisted pairsof wire to carry signals. Upon detecting a first twisted pair which is afailed twisted pair, a switching logic within the PHY-Transceiver isconfigured to reassign signals initially carried on the failed twistedpair to a second twisted pair in the cable.

In one example embodiment a system includes a means for transmitting andreceiving signals over a cable with a local PHY-Transceiver connected atone end of the cable. The cable includes multiple cable channels, and isconnected at the opposite end to a remote PHY-Transceiver. The systemincludes a means for testing the multiple cable channels and a means fordetermining that a first cable channel is inoperable. Additionally, thesystem includes a means responsive to determining that the first cablechannel is inoperative, for causing the remote PHY-Transceivers tonegotiate the second cable channel with the local PHY-Transceiver. Ameans is included in the system for reassigning signals initiallycarried on the first cable channel to a second cable channel to carrysignals in the cable.

In one embodiment, a system includes a means for transmitting andreceiving signals over a cable where the cable includes multiple cablechannels for communicating signals with a remote device. The embodimentfurther include a means for testing the multiple cable channels as wellas a means for determining that a first cable channel is inoperable. Thesystem includes means for negotiating with the remote device to reassignsignal communications from the first cable channel to a second cablechannel in response to determining that the first cable channel isinoperable. Additionally, the embodiment includes means for reassigningsignals initially carried on the first cable channel to the second cablechannel.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings, which are incorporated in and constitute apart of the specification, illustrate various example systems, methods,and other example embodiments of various aspects of the invention. Itwill be appreciated that the illustrated element boundaries (e.g.,boxes, groups of boxes, or other shapes) in the figures represent oneexample of the boundaries. One of ordinary skill in the art willappreciate that in some examples one element may be designed as multipleelements or that multiple elements may be designed as one element. Insome examples, an element shown as an internal component of anotherelement may be implemented as an external component and vice versa.Furthermore, elements may not be drawn to scale.

FIG. 1 illustrates one embodiment of a network device associated withreassigning signals to cable channels.

FIG. 2 illustrates another embodiment of a network device associatedwith reassigning signals to cable channels.

FIG. 3 illustrates one embodiment of a PHY-Transceiver associated withreassigning signals to cable channels.

FIG. 4 illustrates one embodiment of a method associated withreassigning signals to cable channels.

FIG. 5 illustrates another embodiment of a method associated withreassigning signals to cable channels.

FIG. 6 illustrates one embodiment of a computing environment in whichexample systems and methods, and equivalents associated with reassigningsignals to cable channels may be implemented.

Table 1 illustrates one embodiment of signal assignments on a cable withfour twisted pairs of wire.

DETAILED DESCRIPTION

Described herein are example systems, methods and other embodiments thatrespond to a failed cable channel. For example when a failed cablechannel is detected, signals that were directed to the failed cablechannel are reassigned to a different cable channel in the cable. Thus amore robust data transfer over a cable can be achieved by providingcable failover.

In one embodiment, a network device includes a network interface forconnection with a cable that includes cable channels for carryingsignals. The network device communicates over the cable to a remoteterminal connected to the other end of the cable. The cable channels canbe tested periodically to detect whether a cable channel has failed. Forexample, if a wire within the cable breaks, then the wire becomesinoperable and signals can no longer be transferred across the wire.When a channel has been detected as having failed, a switching logicwill reassign signals initially carried on the failed channel to anotheroperable channel.

Thus, when a channel becomes broken or otherwise inoperable, the cablecan be made to still function and the network link does not completelyfail. In another embodiment, if there are no unused or available cablechannels, then the system attempts to assign a subset of the originalcable signals from the failed channel to usable cable channels. Datetransfer is then operated at slower signaling speeds than before thechannel failure to accommodate the fewer channels.

The following includes definitions of selected terms employed herein.The definitions include various examples and/or forms of components thatfall within the scope of a term and that may be used for implementation.The examples are not intended to be limiting. Both singular and pluralforms of terms may be within the definitions.

References to “one embodiment”, “an embodiment”, “one example”, “anexample”, and so on, indicate that the embodiment(s) or example(s) sodescribed may include a particular feature, structure, characteristic,property, element, or limitation, but that not every embodiment orexample necessarily includes that particular feature, structure,characteristic, property, element or limitation. Furthermore, repeateduse of the phrase “in one embodiment” does not necessarily refer to thesame embodiment, though it may.

ASIC: application specific integrated circuit.

CD: compact disk.

CD-R: CD recordable.

CD-RW: CD rewriteable.

DVD: digital versatile disk and/or digital video disk.

IEEE: institute of electrical and electronic engineers.

LAN: local area network.

PCI: peripheral component interconnect.

PCIE: PCI express.

RAM: random access memory.

DRAM: dynamic RAM.

SRAM: static RAM.

ROM: read only memory.

PROM: programmable ROM.

EPROM: erasable PROM.

EEPROM: electrically erasable PROM.

USB: universal serial bus.

WAN: wide area network.

VCT: virtual cable tester.

VoIP: voice over internet protocol.

“Computer-readable medium”, as used herein, refers to a medium thatstores signals, instructions and/or data. A computer-readable medium maytake forms, including, but not limited to, non-volatile media, andvolatile media. Non-volatile media may include, for example, opticaldisks, magnetic disks, flash memory and so on. Volatile media mayinclude, for example, semiconductor memories, dynamic memory, and so on.Common forms of a computer-readable medium may include, but are notlimited to, a floppy disk, a flexible disk, a hard disk, a magnetictape, other magnetic medium, an ASIC, a programmable logic device, a CD,other optical medium, a RAM, a ROM, a memory chip or card, a memorystick, and other media from which a computer, a processor or otherelectronic device can read.

“Logic”, as used herein, includes but is not limited to hardware,firmware, software stored or in execution on a machine, and/orcombinations of each to perform a function(s) or an action(s), and/or tocause a function or action from another logic, method, and/or system.Logic may include a software controlled microprocessor, a discrete logic(e.g., ASIC), an analog circuit, a digital circuit, a programmed logicdevice, a memory device containing instructions, and so on. Logic mayinclude one or more gates, combinations of gates, or other circuitcomponents. Where multiple logical logics are described, it may bepossible to incorporate the multiple logical logics into one physicallogic. Similarly, where a single logical logic is described, it may bepossible to distribute that single logical logic between multiplephysical logics.

An “operable connection”, or a connection by which entities are“operably connected”, is one in which signals, physical communications,and/or logical communications may be sent and/or received. An operableconnection may include a physical interface, an electrical interface,and/or a data interface. An operable connection may include differingcombinations of interfaces and/or connections sufficient to allowoperable control. For example, two entities can be operably connected tocommunicate signals to each other directly or through one or moreintermediate entities (e.g., processor, operating system, logic,software). Logical and/or physical communication channels can be used tocreate an operable connection.

“Signal”, as used herein, includes but is not limited to, electricalsignals, optical signals, analog signals, digital signals, data,computer instructions, processor instructions, messages, a bit, a bitstream, or other means that can be received, transmitted and/ordetected.

Some portions of the detailed descriptions that follow are presented interms of algorithms and symbolic representations of operations on databits within a memory. These algorithmic descriptions and representationsare used by those skilled in the art to convey the substance of theirwork to others. An algorithm, here and generally, is conceived to be asequence of operations that produce a result. The operations includephysical manipulations of physical quantities. Usually, though notnecessarily, the physical quantities take the form of electrical ormagnetic signals capable of being stored, transferred, combined,compared, and otherwise manipulated in a logic, and so on. The physicalmanipulations create a concrete, tangible, useful, real-world result.

With reference to FIG. 1, one embodiment is illustrated of a networkdevice 100 configured to handle failed cable channels. For example, thenetwork device 100 provides communication with a remote device 105connected through a cable 110. The cable 110 can include two or morecable channels (e.g. channels 1, 2, 3, 4, etc.). In one embodiment, eachcable channel is defined by a cable wire that can carry electricalsignals. In other embodiments, a cable channel can be defined as atwisted pair of wire. The network device 100 includes a networkinterface 115 that provides an interface to the cable 110 andcommunicates signals to and from a remote terminal 120. In one or moreembodiments, the network interface 115 and/or the remote terminal 120may include a transceiver.

As will be described in more detail below, the network device 100 isconfigured to provide a cable failover feature that reassigns signalsfrom a failed cable channel to another cable channel in the cable. Inthis manner, data transfer and signal communications over the cable cancontinue even though one channel no longer operates. In the figure, theremote device 105 and the cable 110 are shown in dashed lines becausethey are not part of the network device 100.

In one embodiment, the network device 100 includes a cable tester 125 totest the cable channels in the cable 110 to detect whether a cablechannel has failed. Upon detecting a failed cable channel, a switchinglogic 130 is configured to reassign signals initially carried on thefailed cable channel to a second cable channel in the cable. In someembodiments the cable tester 125 and the switching logic 130 may beincluded in the network interface 115.

In general when the devices communicate, a standard communicationinterface may be used that requires specific signals to be located oncertain channels within the cable 110. For example, the IEEE 802.3i and802.3u standards require the use of a cable with four twisted wirepairs. These standards assign the transmit signals to be on twisted pairthree (e.g. channel three) and the receive signals to be on twisted pairtwo (e.g. channel two). The IEEE 802.3i and 802.3u standards are alsoknown as the 10Base-T and 100Base-TX signaling standards, respectively.

If a channel within the cable 110 become inoperable and if theinoperable channel is carrying a signal according to a standard, thenthe cable 110 (e.g. the link) becomes inoperable or at least producecommunication errors. If the network device 100 follows a standard suchas the IEEE 802.3i standard that only permits certain signals on aspecific channels, then the link will remain broken until the cable 110is physically repaired or replaced.

However, a more robust communication link can be created by the networkdevice 100. When a channel fails, the network device 100 is configuredto check for unused channels within the cable 110 that are stillfunctional. If there are unused channels, then the network device 100can transfer signals from the inoperable channel to an operable unusedchannel. Even though the signaling standard is not strictly followedsince some signals are not on their assign channels, the link remainsoperational.

With continued reference to FIG. 1, in one embodiment for testing thechannels, the cable tester 125 is configured to transmit a testsignal(s) on a cable channel and then measure signal properties from thecable channel. Based on the signal properties, the cable tester 125 candetermine if the channel is functioning or not. For example, a testsignal can be transmitted on a channel and the cable tester 125 cancalculate a length the test signal travels. The length the test signaltravels will correspond to where a channel ends and thus where the wirehas failed (e.g. a break point in the wire).

For example, the cable length may be calculated by the cable tester 125by first causing the network interface 115 to send a test pulse to aselected cable channel. Next, the time lapse from sending the test pulseto receiving a reflected pulse back at the network interface 115 ismeasured. By knowing the time lapse and the speed of the signal, around-trip distance traveled is calculated. Dividing the distance by twogives a one-way distance of the channel. A shorter than expecteddistance can indicate a cable break. The cable tester 125 can also beconfigured to measure an amplitude of the reflected signal derived fromthe test signal. A measured amplitude that does not fall within anexpected range may further indicate that the cable channel is notoperating properly. The cable tester 125 then determines if the cable110 has a failed channel based on the signal amplitudes and/or themeasured lengths of each channel. In one embodiment, the cable tester125 is a Virtual Cable Tester (VCT) produced by Marvell SemiconductorInc.

When the cable tester 125 detects an inoperable cable channel, a signalcan be set that causes the switching logic 130 to make channelreassignments. For example, the switching logic 130 will attempt toreassign signals initially carried on the inoperable channel to anothercable channel that is functioning. In one embodiment, the switchinglogic 130 can first try to identify any unused channels on the cable 110and if available, then reassign the signals from the failed channel tothe unused channel. The network interface 115 is then reconfigured tocommunicate the signals initially assigned on the failed channel to theunused channel. The network interface 115 will also negotiate with theremote terminal 120 to make the same channel reassignments tosynchronize communications.

By reassigning the signals to an unused channel, it is possible for thenetwork interface 115 to still transmit and receive signals to and fromthe cable 110. In other embodiments, when all the channels on the cable110 are being used and an inoperable channel is detected, the cable 110may still be operable by reassigning multiple channels. In oneembodiment, the reassigning can include reconfiguring the networkinterface 115 to communicate signals using a different communicationprotocol than originally used. For example, the switching logic 130 canbe configured to cause the network interface 115 to reconfigure signalcommunications from a first communication protocol to a differentcommunication protocol that uses fewer cable channels. In this manner,the failed cable channel can be avoided with a protocol that does notuse the failed channel. In another embodiment, the network interface 115may have to interface with the cable 110 at slower speeds so as to useonly the functioning channels and avoid the failed channel.

Consider for example one embodiment where the network device 100implements the IEEE 802.3ab standard on the cable 110 that includes fourtwisted pairs of wires. This standard, also known as 1000Base-Tsignaling, transmits data at the rate of one gigabit per second. Asshown below in table 1, all four channels of the cable 110 (e.g.connected to eight pins) are used when implementing the standard. Inthis case, if a channel is found to be inoperable, then there are nounused/spare channels and the 1000Base-T standard will not function withthe inoperable cable 110. However, the network interface 115 can bereconfigured to communicate over the cable 110 to operate with fewerchannels at slower signaling speeds using a different protocol. Table 1is shown as an example of one embodiment only and other embodiments mayuse other standards with a different number of twisted pairs or evencables not using twisted wire pairs, for example fiber optic cables.

For example, when all four twisted pairs are being used and one twistedpair fails, then the network interface 115 can be reconfigured tooperate with the cable 110 using only two twisted pairs (e.g. twochannels) by changing the communication protocol to one that uses fewerthan four channels (e.g. the IEEE 802.3u (100Base-TX) standard). Asshown in table 1, the 100Base-TX standard uses twisted wire pairs twoand three, with pairs one and four unused. Since only two channels areneeded with the 100Base-TX protocol, the other channels can fail andcommunications can continue. Thus in one embodiment, when the cabletester 125 detects a failed channel, the switching logic 130 can switchcommunications from the 1000Base-T standard to the 100Base-TX standardand use only two channels/cable pairs. Of course, switching to the100Base-TX standard causes the network interface 115 to reduce the datatransmission speed of the cable 110 from one gigabit/second to onehundred megabits/second.

TABLE 1 RJ 45 Pair # 10Base-T Signal/ 1000Base-T Pin # (channel) WireColor 100Base-TX Signal Signal 1 3 White/Green Transmit+ BI_DA+ 2 3Green Transmit− BI_DA− 3 2 White/Orange Receive+ BI_DB+ 4 1 Blue UnusedBI_DC+ 5 1 White/Blue Unused BI_DC− 6 2 Orange Receive− BI_DB− 7 4White/Brown Unused BI_DD+ 8 4 Brown Unused BI_DD−

In another example, consider the network device 100 implementing the1000Base-T standard, which uses all four channels in the cable 110. Ifchannel three was determined to be inoperable, then the 100Base-TXstandard could not be implemented directly by the network device 100since channel three is part of the standard. In this case, the switchinglogic 130 may determine that because there are still at least two goodpairs of channels (e.g. channels one, two, and four) then any two ofthese channels may be used to implement a signaling standard equivalentto the 100Base-TX standard. For example, cable channel two may still beused to carry signals Receive+/Receive− according to the standard.However, channel 1 may be selected by the switching logic 130 to carrysignals Transmit+/Transmit−. Because channel three does not carrysignals Transmit+/Transmit−, the reassignment does not strictly followthe 100Base-TX standard as shown in table 1 but still uses two channels.

In another example, the cable 110 made of four twisted wire pairs mayhave twisted pairs one and two completely cut open and totally unusable.Twisted pair three may be completely operable at gigabit speeds,however, twisted pair four may be so badly damaged that the cable tester125 determines that pair four may only operate at 10Base-T (10 megabit)speeds. In this example, the switching logic 130 can be configured toassign the 10Base-T signals Transmit+/Transmit− to twisted pair threeand signals Receive+/Receive− to pair four. Of course, this does notexplicitly follow the 10Base-T standard, but the network device 100 maystill be operational with the cable 110.

When the network device 100 makes a channel assignment change, theremote device 105 must be aware of the change to properly communicatethrough the cable 110 with the network device 100. Thus in oneembodiment, the channel reassignments will operate if the remote device105 is able to detect that signals have been reassigned to new channellocations on the cable 110. In another embodiment, the network device100 is configured to negotiate a new channel assignment or cause theremote device 105 to accept the new channel assignments. This will befurther described with reference to FIG. 2.

It will be appreciated that in one or more embodiments the networkdevice 100 may be implemented in an integrated circuit, an applicationspecific integrated circuit (ASIC), a network interface, and so on. Inanother embodiment, the network device 100 can be implemented as anEthernet device that connects a host to a network. In one example, thenetwork device 100 is a PHY-Transceiver. In another embodiment, thenetwork device 100 is configured to be compliant with one or morecommunication protocols, for example, Institute of Electrical andElectronic Engineers (IEEE) 802.3ab, 802.3i, 802.3u, and so on. In otherembodiments, the network device 100 can be configured to be compliantwith any suitable standard. In one embodiment the network interface 115is configured to connect to an Ethernet cable (e.g. Category 5, 6 and soon).

With reference to FIG. 2, another embodiment of the network device 100is shown. The network device 100 includes a negotiation logic 205 tonegotiate new cable assignments with the remote device 105. Thenegotiation will assure that if the switching logic 130 decides toassign a signal from an inoperable channel to a new channel, the remotedevice 105 is in agreement with the network device 100 or at least awareof the channel reassignment(s). The negotiation logic 205 may use atleast one channel that is operational (e.g. has not failed) tocommunicate with the remote device 105 connected to the other end of thecable 110. If all the channels are being used before a failed channel isdetected by the cable tester 125, then the negotiation logic 205 willnegotiate assigning fewer signals on fewer cable channels in the cable110. If a channel assignment will affect the communication speed, thenegotiation logic 205 will negotiate operating the cable channels at alower operating speed.

In another embodiment, the network device 100 further includes a timer210 to control activation of the cable tester 125. The timer 210 may beconfigured to determine a time value since previous signal activity on acable channel. The time since the last signal activity on a channel maybe used to prompt the cable tester 125 to test that cable channel todetermine if the channel is operational or not. In one example, thecable tester 125 will initiate a test when the time value for thatchannel exceeds a predetermined time value.

In some embodiments, the network interface 115 is configured to connectto a cable having four twisted pairs of wire where each pair is a cablechannel. In one embodiment, the network interface 115 further includes aport 215 that is compatible with an RJ45 connector. In one embodiment,the port 215 includes eight pins grouped into four pairs of pins forconnecting to the four cable channels (twisted pairs) in accordance withthe pin assignments shown in Table 1. For example, the switching logic130 is configured to connect the first cable channel to pin numbers fourand five, the second cable channel to pin numbers three and six, thethird cable channel to pin numbers one and two, and the forth cablechannel to pin numbers seven and eight. The switching logic 130 isoperable to reassign a failed cable channel on cable channels two orthree to channels one or four. Of course, different pin assignments willbe used for different cables and/or different communication protocols.

FIG. 3 illustrates one embodiment of a PHY-Transceiver 300 that isconfigured to reassign signals between cable channels when a channelfails. In that regard, the PHY-Transceiver 300 is implemented to includethe switching logic 130. In one embodiment, as discussed above for thenetwork device 100, the PHY-Transceiver 300 is configured to communicateto a remote terminal over a cable having twisted wire pairs. ThePHY-Transceiver 300 includes a port 215 to connect to the cable. In oneembodiment, the port 215 is compatible with an RJ45 connector. When thePHY-Transceiver 300 detects a failed twisted pair, the switching logic130 will reassign signals initially carried on the failed twisted pairto another operational twisted pair.

As discussed above for the network device 100 (shown in FIGS. 1 and 2),the PHY-Transceiver 300 may include a cable tester 125 to test the cableto detect a failed twisted pair. The timer 210 shown in FIG. 2 may beincluded within the PHY-Transceiver 300 to prompt the cable tester tobegin testing a channel. The PHY-Transceiver 300 may also include anegotiation logic 205 (shown in FIG. 2) to negotiate another twistedpair with a remote PHY-Transceiver connected to the other end of thecable. The negotiation logic 205 may negotiate for a cable channelsignal assignment as discussed above. In one embodiment, a signal toreassign channels sent from the PHY-Transceiver 300 to the remotePHY-Transceiver will cause the remote PHY-Transceiver to reassignsignals at the remote PHY-Transceiver according to an assignmentgenerated by the switching logic 130.

FIG. 4 illustrates one embodiment of a method 400 associated withreassigning signals to a cable channel. At block 405, the method beginsby transmitting and receiving signals over a cable, where the cableincludes multiple cable channels. In one embodiment, the transmittingand receiving is performed by a local PHY-Transceiver connected at oneend of the cable that communicates with a remote PHY-Transceiverconnected to the cable.

The method 400 continues at 410 by determining that a cable channel isinoperable. The cable channel may be determined to be inoperable asdiscussed above. In one embodiment, test signals are transmitted over achannel and signal properties are measured. Based on the measuredproperties, it can be determined whether the channel is functioning. Ifthe cable channel is determined to be inoperable, then at block 415,signals initially carried on the inoperable cable channel are reassignedto an operable cable channel in the cable.

As discussed above in one embodiment, the channel reassignment may bemade according to any suitable IEEE signaling standard, cable speed,and/or any suitable cable. The channel reassignment may result inoperating the cable channel with different cable channel speeds thanbefore the reassignment. In some embodiments, fewer channels and signalsmay be assigned to the cable after the reassignment than initially used.

In another embodiment, the method 400 may include testing the cablechannels to determine if the channels are all operational. A test signalmay be transmitted from a local PHY transceiver on the failed cablechannel to measure signal amplitude, calculate a length of the cable inwhich the test signal travels, and/or determine the cable channel statusbased on the measured amplitude and the length. The method 400 mayfurther include determining a time since the last signal activity on acable channel. If the time passes a predetermined time value, the cablechannel is then tested.

FIG. 5 illustrates another embodiment of a method 500 associated withreassigning signals of a cable when a cable channel fails. The methodbegins, at 505, by transmitting and receiving signals to a cablechannel. At 510, one or more cable channels are tested. A determinationis made, at 515, whether a cable channel was found inoperable whentested. If the cable channel was determined to be operating as normal,then flow returns back to block 510 where other channels are testedand/or the method waits until testing is re-initiated.

If a cable channel was found inoperable at block 515, then flowcontinues to block 520 where a new cable channel(s) are assigned. In oneembodiment, the reassignments may be made as discussed above. Forexample, signals from a failed channel are reassigned to anotheravailable channel. At 525, a determination is made as to whether fewerchannels were assigned subsequent to the inoperable channel beingdetected at 515. This can be the case where there are no availableunused channels left in the cable and the communication protocol ischanged in order to use fewer channels. If there are not fewer channelsafter the reassignment, then the new signal channels are rerouted, at530, with the same signaling speed as originally used (e.g. before thecable channel failed). However, if fewer channels are reassigned thanbefore, then the new signal channels are rerouted, at 535, with a slowersignaling speed than originally used.

It will be appreciated that in one embodiment, the methods herein may beimplemented as computer executable instructions. Thus, in one example, acomputer-readable medium may store computer executable instructions thatif executed by a machine (e.g., processor, device) cause the machine toperform a method that includes detecting a failed cable channel andreassigning signals to the cable channels.

FIG. 6 illustrates an example computing device in which example systemsand methods described herein, and equivalents, may be implemented andoperate. The example computing device may be a computer 600 thatincludes a processor 605, a memory 610, and input/output ports 615operably connected by a bus 620. In one example, the computer 600 mayinclude a reassignment logic 625 configured to reassign signals to cablechannels. In one embodiment, the reassignment logic 625 is implementedas the switching logic 130. A network device 650 is implemented as thenetwork device 100 (of FIG. 1 or 2), the PHY-Transceiver 300 (of FIG.3), or combinations and equivalents thereof. In different examples, thenetwork device 650 may be implemented in hardware, software, firmware,and/or combinations thereof.

The reassignment logic 625 provides a means (e.g., hardware, storedsoftware, firmware) of identifying an inoperable cable channel andreassigning signals on that channel to another channel. In operation,the reassignment logic 625 identifies an inoperable cable channel in acable (not shown) that is in communication with the reassignment logicor to the computer 600 through an input/output port 615. After aninoperable channel is detected, the reassignment logic will reassign thesignal from the inoperable channel to another operable channel.

The logic may be implemented, for example, as an ASIC or other type ofcircuit. The logic may also be implemented as computer executableinstructions that are stored and processed by a processor.

Generally describing an example configuration of the computer 600, theprocessor 605 may be a variety of various processors including dualmicroprocessor and other multi-processor architectures. A memory 610 mayinclude volatile memory and/or non-volatile memory. Non-volatile memorymay include, for example, ROM, PROM, EPROM, EEPROM, and so on. Volatilememory may include, for example, RAM, SRAM, DRAM, and so on.

A disk 635 may be operably connected to the computer 600 via, forexample, an input/output interface (e.g., card, device) 640 and theinput/output port 615. The disk 635 may be, for example, a magnetic diskdrive, a solid state disk drive, a floppy disk drive, a tape drive, aZip drive, a flash memory card, a memory stick, and so on. Furthermore,the disk 635 may be a CD-ROM drive, a CD-R drive, a CD-RW drive, a DVDROM, and so on. The memory 610 can store a process 645 and/or a data630, for example. The disk 635 and/or the memory 610 can store anoperating system that controls and allocates resources of the computer600.

The bus 620 may be a single internal bus interconnect architectureand/or other bus or mesh architectures. While a single bus isillustrated, it is to be appreciated that the computer 600 maycommunicate with various devices, logics, and peripherals using otherbusses (e.g., PCIE, 1394, USB, Ethernet). The bus 620 can be typesincluding, for example, a memory bus, a memory controller, a peripheralbus, an external bus, a crossbar switch, and/or a local bus.

The computer 600 may interact with input/output devices via the I/Ointerfaces 640 including the reassignment logic 625 and the input/outputports 615. Input/output devices may be, for example, a keyboard, amicrophone, a pointing and selection device, cameras, video cards,displays, the disk 635, the network devices 650, and so on. Theinput/output ports 615 may include, for example, serial ports, parallelports, and USB ports.

The computer 600 can operate in a network environment and thus may beconnected to the network devices 650 via the i/o interfaces 640, and/orthe i/o ports 615. Through the network devices 650, the computer 600 mayinteract with a network. Through the network, the computer 600 may belogically connected to remote computers. Networks with which thecomputer 600 may interact include, but are not limited to, a LAN, a WAN,and other networks.

While example systems, methods, and so on have been illustrated bydescribing examples, and while the examples have been described inconsiderable detail, it is not the intention of the applicants torestrict or in any way limit the scope of the appended claims to suchdetail. It is, of course, not possible to describe every conceivablecombination of components or methodologies for purposes of describingthe systems, methods, and so on described herein. Therefore, theinvention is not limited to the specific details, the representativeapparatus, and illustrative examples shown and described. Thus, thisapplication is intended to embrace alterations, modifications, andvariations that fall within the scope of the appended claims.

To the extent that the term “includes” or “including” is employed in thedetailed description or the claims, it is intended to be inclusive in amanner similar to the term “comprising” as that term is interpreted whenemployed as a transitional word in a claim.

What is claimed is:
 1. A networking device, comprising: a networkinterface to connect to an active cable and communicate over the activecable to a remote terminal, where the active cable includes two or morecable channels to carry signals; a cable tester to test a first cablechannel of the two or more cable channels upon a time value for thefirst cable channel exceeding a predetermined threshold value forinactivity, wherein the cable tester is configured to detect whether thefirst cable channel has failed; and a switching logic to reassignsignals initially carried on the first cable channel to a second cablechannel in the active cable upon detecting that the first cable channelhas failed.
 2. The network device of claim 1, further includingnegotiation logic to negotiate with the remote terminal to reassign thesignals from the first cable channel to the second cable channel.
 3. Thenetworking device of claim 2, wherein the negotiation logic isconfigured to negotiate operating the two or more cable channels at alower operating speed, upon detecting the failed cable channel.
 4. Thenetworking device of claim 1, wherein the switching logic is configuredto cause the network interface to reconfigure signal communications froma first communication protocol to a different communication protocolthat does not use the failed cable channel.
 5. The networking device ofclaim 1, further comprising a timer configured to monitor the two ormore cable channels while the two or more cable channels are designatedto actively carry communications.
 6. The network device of claim 1,wherein the network interface is configured to communicate signals tothe active cable at a plurality of speeds including at least 10 gigabitsper second.
 7. A method comprising: transmitting and receiving signalsover an active cable, wherein the active cable includes multiple cablechannels; determining that a first cable channel is inoperable bytesting the first cable channel upon a time value for the first cablechannel exceeding a predetermined threshold value for inactivity andusing at least a test signal, wherein the test signal is transmitted onthe first cable channel while the active cable is designated as active;and reassigning signals initially carried on the first cable channel toa second cable channel in the active cable after the first cable channelis determined as inoperable based on at least the test signal.
 8. Themethod of claim 7, wherein the transmitting and receiving is performedby a local PHY-Transceiver connected at one end of the active cable thatcommunicates with a remote PHY-Transceiver connected to the activecable; the method further including: responsive to determining that thefirst cable channel is inoperative, causing the remote PHY-Transceiverto negotiate the reassignment of signals to the second cable channel. 9.The method of claim 8, wherein causing the remote PHY-Transceiver tonegotiate the second cable channel includes negotiating a slowersignaling speed for signals transmitted and received from the activecable.
 10. The method of claim 7, wherein the reassigning includesreconfiguring signal communications from a first communication protocolto a different communication protocol that does not use the inoperablecable channel.
 11. The method of claim 7, wherein the signals aretransmitted and received at a speed of at least 10 gigabits per second.12. The method of claim 7, wherein the transmitting includestransmitting the signals at about a 1000 Megabits/second speed beforethe reassigning and at about a 10 Megabits/second speed or about a 100Megabits/second speed after the reassigning.
 13. The method of claim 7,further including negotiating with a remote terminal so that fewer cablechannels are used for communication than before the first cable channelwas determined inoperable.
 14. A PHY-Transceiver comprising: a port toconnect to an active cable and communicate over the active cable to aremote PHY-Transceiver, where the active cable includes two or moretwisted pairs of wire to carry signals; a cable tester to test the twoor more twisted pairs of wire to detect a twisted pair that has failed,wherein the cable tester is configured to test at least one of thetwisted pairs upon a time value of previous signal activity for thetwisted pair exceeding a predetermined time value; and a switching logicto reassign signals initially carried on a first twisted pair of wire inthe active cable to a second twisted pair of wire in the active cableupon detecting that the first twisted pair of wire has failed.
 15. ThePHY-Transceiver of claim 14, further including negotiation logic tonegotiate the second twisted pair with the remote PHY-Transceiver. 16.The PHY-Transceiver of claim 15, wherein the negotiation logic isconfigured to negotiate to operate the twisted pairs at a loweroperating speed, upon detecting the failed twisted pair.
 17. ThePHY-Transceiver of claim 14, wherein the PHY-Transceiver is configuredto transmit and receive signals at a plurality of speeds including 10gigabits/second.
 18. The PHY-Transceiver of claim 14, wherein theswitching logic is configured to reassign signals by causing thetransceiver to reconfigure signal communications from a firstcommunication protocol to a different communication protocol that doesnot use a twisted pair that has failed.
 19. The PHY-Transceiver of claim14, further comprising a timer configured to monitor the two or moretwisted pairs in the active cable and to maintain a time value for eachtwisted pair that indicates a time since detecting previous signalactivity, where the timer is configured to monitor the two or moretwisted pairs while the two or more twisted pairs are designated toactively carry signals.
 20. The PHY-Transceiver of claim 14, wherein theswitching logic is further configured to reconfigure the PHY-Transceiverto reroute signals from the failed twisted pair to the second twistedpair.